The propagation speed of a positive lightning return stroke Academic Article uri icon


  • The first direct determination of the propagation speed of a lightning return stroke lowering positive charge to ground has been made. This stroke was the third of eight otherwise negative strokes in a triggered lightning flash initiated at the Kennedy Space Center, Florida. Two independent optical systems, one photographic and the other photoelectric, yielded common recordings for the third and fourth strokes; the respective twodimensional return stroke propagation speeds were 1.0 vs. 0.93 108 m/s for the positive (third) stroke and 1.0 vs. 1.0 108 m/s for the fourth stroke. Using fast electricfield data, we estimated the positive stroke peak current to be 21 kA. Photoelectric data only yielded propagation speeds of 1.4, 1.6, 1.2, 1.3, 1.0 and 0.90 108 m/s for the first, second and fifth through eighth return strokes, respectively. All propagation speeds were evaluated over 850 m of channel near ground and have an error estimate of 1015%. For this positive stroke, we found a return stroke propagation speed typical of negative strokes. Whether positive return strokes, in general, travel at typical negative return stroke speeds must await future measurements. Copyright 1987 by the American Geophysical Union.

published proceedings

  • Geophysical Research Letters

author list (cited authors)

  • Idone, V. P., Orville, R. E., Mach, D. M., & Rust, W. D.

complete list of authors

  • Idone, Vincent P||Orville, Richard E||Mach, Douglas M||Rust, W David

publication date

  • January 1, 1987 11:11 AM